<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        const arr =[1,2,3,4]
        const arr2 = [5,6,7,8]
        /* concat方法 */
        /* const nearr=arr.concat(arr2) */
        const nearr=[...arr,...arr1]
    document.write(nearr)
    </script>
</body>
</html>